The Wolverhampton site is to close with 70 job losses, with another 160 jobs lost at other sites in the UK – yet to be decided by the company.
BAE says once the Wolverhampton site completes its existing contracts, it plans to outsource all future manufacturing requirements.
Prospect negotiator Tony Hammond said the cuts were another nail in the coffin of military equipment manufacturing in the UK.
“It shows again that defence cuts are hitting the private sector. The loss of valuable skills is a great concern to Prospect and is yet another blow to the UK’s defence infrastructure.”